An objective in cancer surgery is the removal of tumor tissue together with a safety margin of tumor-free tissue around the tumor tissue. Some cancers have a preferred direction of growth. For example, breast cancer often grows along the lobules, in a direction perpendicular to the pectoral muscle. It is standard clinical practice to remove a volume of cylindrical shape from the breast, extending from the pectoral muscle to the skin.
Reporting and planning of such surgeries is almost exclusively performed by manually applying (with a felt pen for instance) incision lines directly on the skin of the patient which can then be recorded by a taking a photograph for instance. On occasions, the incision lines are applied as annotations on a pre-printed paper form where a generic representation of the relevant organ is shown. These lines are to capture a contour or shape of the cancer in a plan view. In other words, the shapes are only drawn in two dimensions (as outlined from one viewing direction). But the three dimensional extent of the volume to be removed and the orientation thereof within the surrounding tissue is not explicitly recorded and must therefore be mentally estimated by the reader of such reports.